Foreign



J. E. FLIPSE March 10, 1964 APPARATUS FOR LOADING AND UNLOADING CARGO Filed Feb. 1961 3 Sheets-Sheet 1 ATTORNEYS March 10, 1964 J. E. FLIPSE APPARATUS FOR LOADING AND UNLOADING CARGO Filed Feb. 15, 1961 3 Sheets-Sheet 2 BY g mma W ATTORNEYS United States Patent 3,124,2tl9 APPARATUS FGR LGADKNG AND UNLGADENG CARGO John E. Flipse, Gloucester, Va, assignor to Newport News Shipbuilding and Dry Dock Company, Newport News, Va., a corporation of Virginia Filed Feb. 15, 1961, Ser. No. 8%,49'tl 3 Claims. (Cl. 1807) The present invention relates to a new and novel method and apparatus for loading and unloading cargo in ships wherein cargo support means within the ship are provided with a gas-cushion therebeneath which facilitates lateral movement of the cargo support means to enable a much simpler spotting of cargo in the hold of a ship than has heretofore been possible.

Cargo ships are usually provided with a plurality of hatches which open generally in the central portion of the various decks of the ship. Cargo which is loaded onto the ship is normally lowered through these hatches to rest in a central portion of the ship. It is then, of course, necessary to move some of the cargo laterally of the hatches along the decks so as to completely fill the hold of the ship. The present invention is particularly concerned with the problem of moving the cargo laterally along the decks after the cargo has been lowered into place through conventional hatches.

Many eiforts have been made in the prior art to provide means for simplyfying the mode of transferring the cargo laterally within the ship once it is lowered into position. Some of the proposed solutions to this problem include rolling decks, conveyors, overhead monorails, rollers on the cargo support means which may cooperate with suitable track means and snatch blocks are also employed for this purpose.

While these arrangements have met with limited success in performing the desired end result, the arrangements are excessively complex, bulky and expensive, and are subject to malfunctioning and in some cases require quite a bit of maintenance. It is accordingly evident that there is a long-standing problem in the art to provide a truly simple, inexpensive and effective means for easily moving the cargo into position and properly spotting it in the cargo hold.

The aforementioned prior art methods of loading and unloading ships have been utilized with break bulk cargo which is generally stacked on pallets which are then moved into the desired position. This type of operation can be carried out with conventional ships having central hatches disposed through the decks thereof. However, these conventional types of ship constructions are not suitable for use with a modern development wherein the cargo container may comprise the trailer portion of a tractor-trailer land vehicle. With this latter arrangement, the entire upper portion of a tractor-trailer combination is removable from the truck bed and this entire container is lowered into place in the ship, whereupon it can be subsequently removed and placed back upon the bed of another trailer.

These large trailer containers are not usually loaded through the conventional batches of ships since it is excessively difiicult to spot the container in position in the hold once it is lowered in position.

As a result, ships carrying this type of cargo are usually 3,124,299 Patented Mar. 10, 1964 designed to eliminate the decks and the containers are vertically stacked in the hold one upon the other such that the reinforced corners of the various containers support the containers thereabove. This arrangement, of course, requires an especially constructed ship which, of course, is an undesirable feature since it would be preferable to employ the conventional construction which would thereby permit such construction to be of more versatile utility. Accordingly, it is a further feature of the invention to provide an arrangement wherein these types of containers can be employed in a conventional cargo ship having decks with central hatches formed therethrough.

In the present invention, novel cargo support means is provided wherein an enclosed space is provided beneath the cargo support means, outlet means being provided in this closed space for releasing gas under pressure and producing a gas-cushion beneath the cargo support means. The cargo support means is then fioatingly supported upon this cushion in accordance with the so-called ground effect principle.

The as-cushion thus produced is adapted to support the cargo support means slightly above the associated deck portion, and when so supported, the cargo support means may be readily moved in a lateral direction merely by applying manual pressure to the side of the cargo and its support means. Even though the support means may be of a relatively large size such as a trailer container, the load may be readily shifted laterally by a single man pushing on the side of the container. It is accordingly evident that the cargo may be spotted with a minimum of effort and requiring a minimum number of operating personnel to handle the operation.

An important feature of the present invention is the fact that the individual cargo support means themselves are not provided with a source of energy for producing the gas-cushion. It would be excessively expensive to provide a suitable engine or other means for providing the gas-cushion in each of the individual cargo support means. The cargo support means themselves are merely provided with an outlet means for directing gas downwardly along with conduit means connected therewith, and an attaching means is provided for connecting the outlet means with an external source of gas under pressure.

With this arrangement, the ship itself may be provided with a suitable source of gas under pressure which is reaidly available in such ships, and flexible conduits may be provided for connecting the source of pressure to the conduits and outlet means of each of the cargo support means. Suitable valve means is also provided for controlling the flow of gas under pressure such that the cargo support means may be lifted and lowered at will, the flexible connecting means of course permitting ready maneuvering of the cargo support means about the decks of the ship.

When employing the trailer container cargo support means, the container may be provided with attaching means on the outer surface thereof such that a small powered vehicle may be employed for maneuvering the container about the deck of the ship. The vehicle is provided with cooperating attaching means which enables the vehicle to be secured to the container whereupon the container may be readily moved from place to place merely by operating the vehicle.

It has been found that body means which are supported upon a gas-cushion must be relatively carefully balanced in order to maintain roper stability. If the body means is unbalanced when resting on its gas-cushion, the body means will tend to tilt, and this tilting movement will produce forces tending to move the body means in a lateral direction.

More often than not, the cargo loaded on the cargo support means of the present invention will not be perfectly balanced, and in many cases may be considerably unbalanced. It is accordingly essential to provide a means for properly balancing and stabilizing the cargo support means. In the present invention, the open space beneath the cargo support means within which the outlet means is disposed is divided into a plurality of separate chambers, and valve means is provided for controlling the gas flow into each of these chambers. By suitably adjusting the gas fiow into the various chambers, the forces acting on the under surface of the cargo support means may be controlled so as to produce a stabilized condition of the cargo support means even though the load thereon may be unbalanced. The provision of the valve means for balancing the cargo support means enables an operator to completely stabilize the support means such that it can be readily controlled when moving it in a lateral direction.

An object of the present invention is to provide a new and novel apparatus for loading and unloading cargo in ships which eliminates the complicated and bulky structures employed in the prior art for moving the cargo laterally in the hold thereby substantially reducing the cost and weight as well as the space required for such apparatus.

A further object of the invention is the provision of a new and novel apparatus for unloading and loading cargo in ships which is highly versatile and can be employed in handling break bulk cargo as well as trailer containers.

A further object of the invention is to provide apparatus for loading and unloading cargo in ships which includes means for balancing and stabilizing the cargo sup port means even though the load thereon may be considerably unbalanced.

A still further object of the invention is to provide a novel method for loading and unloading cargo in ships which permits cargo to be quickly and easily spotted within the hold.

Other objects and many attendant advantages of the invention will become more apparent when considered in connection with the specification and accompanying drawings, wherein:

FIG. 1 is a transverse section through a ship illustrating the invention in a somewhat schematic manner;

FIG. 2 is a top perspective view of one form of cargo support means according to the present invention;

FIG. 3 is a section taken along line 3-3 of FIG. 4 looking in the direction of the arrows;

FIG. 4 is a section taken along line 4-4 of FIG. 3 looking in the direction of the arrows;

FIG. 5 is a view of a portion of the cargo support means shown in FIG. 2 illustrating the valving arrangement;

FIG. 6 is an enlarged view of a portion of the apparatus shown in FIG. 4 more clearly illustrating the outlet means employed therein;

FIG. 7 is a perspective view illustrating the invention as applied to a trailer container;

FIG. 8 is a top view partially broken away of a portion of the maneuvering vehicle shown in FIG. 7 illustrating the means for securing the vehicle to the side of the trailer container;

FIG. 9 is an end view partially broken away illustrating a portion of the construction of the trailer container and its relation to the bed of the trailer; and

FIG. 10 is a bottom view of the trailer container shown in F1GS.7 and 9.

Cir

Referring now to the drawings wherein like reference characters designate corresponding parts throughout the several views, a conventional ship includes a hull indicated generally by reference numeral 20, the hull including frames 21 upon which the hull plates 22 are supported. A top deck 25 is provided, and the space defined by the hull 2t) and the top deck 25 comprises the hold of the ship. A plurality of cargo decks 26, 27 and 23 extend horizontally through the hull and may be divided into hold sections by transverse bulkheads in a conventional manner.

A conventional hatchway extends vertically through the hold to provide access to the various decks and includes a hatch opening 30 surrounded by a hatch coaming 31 in the top deck 25 and a plurality of aligned hatch openings 32 and 33 are provided in the cargo decks 26 and 27 respectively.

Conventional hoisting machinery or cranes 35 are provided on the top deck 25 of the ship for raising and lowering the cargo through the hatch openings in the various decks. For the purpose of illustration, a hatch cover 36 is disposed in operative position so as to close the hatch opening 33. The ship is illustrated as being in loading position adjacent a conventional dock indicated generally by reference numeral 37.

\eferring now to FIGS. 2-6, a first form of the cargo support means is illustrated and as seen in FIG. 2, this cargo support means is indicated generally by reference numeral 4% and includes an upper supporting surface 41 which may be defined by a plurality of parallel members 41' as shown, these members being supported upon a generally rectangular framework defined by side wall members 42, 43, 44 and as seen most clearly in FIG. 4, these frame members being connected in end-to-end relationship with one another. It is, of course, apparent that members 41' as well as members 42-45 may be constructed of any suitable material such as metal or wood and suitably connected to one another in a conventional manner.

As seen in FIG. 4, a wall 46 extends parallel with wall 43 between the walls 42 and 44 and defines a space 47 for a purpose hereinafter described. It will further be noted that the walls 42, 44, 45 and 46 define a closed space beneath the cargo support surface 41, this space opening downwardly relative to the cargo support means.

As seen most clearly in FIG. 4, the enclosed space in the under surface of the cargo support means is divided into a plurality of chambers by a pair of parallel wall 5d and 51 extending between walls 45 and 46, and a pair of walls 52. and 53, wall 52 extending between walls 42 and 50, and wall 53 extending between walls 44 and 51. With this arrangement, the space is divided into four symmetrical chambers 55, 56, 57 and 58. The number of chambers may be varied, but it is important that they be in a symmetrical relationship since the positioning and shape of the chambers determines the ability of the device to be balanced and stabilized as will hereinafter appear.

It will also be noted that a pair of cross brace members 6% and 61 extend in criss-cross relation over each of the chambers 55, 56, and 57 and 58 and are secured to the under surface of the upper support surface 41 as seen in FIG. 3. These cross brace members 60 and 61 are provided for rigidifying and reinforcing the structure.

Means is provided for rendering each of the chambers 55, 56, 57 and 58 air-tight on the sides and upper portions thereof, and for this purpose an air-tight layer of material is disposed along the side walls and top walls of each of the chambers. This air-tight layer may be seen most clearly in FIG. 3 wherein a portion of the chambers 56 and 58 are visible.

While the layer may take different forms, a preferred form is to provide a thin layer of plastic material which can be easily applied to the desired surfaces of the surrounding framework.

As seen in FIG. 3, a first air-tight layer 65 may be supported along the inner surfaces of walls 44- and '51 of the framework, as well as along walls 46 and 53 thereof. It will be noted that the layer 65 may surround the cross brace members 60 and 61 and the under surface of the upper supporting portion 411 of the cargo support means. In a similar manner, a layer 66 is provided for chamber 56, this layer 66 extending along the inner surfaces of walls 50 and 42 as Well as the inner walls 46- and 52.

Referring to FIGS. 6, an enlarged view of layer 65 is illustrated, and as noted in this figure, the portion of the layer which extends up along the inner surface of wall 44 joins the portion of the layer disposed on the under surface of the upper portion 41 of the cargo support means through the intermediary of a curved portion 65. Such curved portions enable the layer to change directions at intersecting wall portions and at the same time serve to retain an air-tight seal. The layers associated with the various chambers may be secured in position by suitable means such as gluing or the like, and are thereby permanently retained in operative position.

As seen in FIG. 4, layers 67 and 68 are provided in each of the chambers 55 and 57, layers 67 and 63 being in all ways identical with the aforedescribed layers 65 and 66. Each of the air-tight layers 65, '66, 67 and 68 is of a substantially rectangular dome-shaped configuration and opens downwardly so as to permit the escape of gas under pressure only in a downward direction from each of the chambers.

As seen most clearly in FIG. 6, the lower edge of each of the air-tight layers in the various chambers terminates at a point spaced above the lower edge of the associated walls. The space between the lower edge of the air-tight layers and the lower edge of the walls accommodates the outlet means which as seen in FIG. 6 may be in the form of a hollow conduit 75 held in place by flexible straps 71 which are secured to the surrounding wall portions. Conduit 7G is provided with a plurality of openings 73 which are directed inwardly toward a point beneath the central portion of the chamber whereby gas is directed under pressure through these various openings '73 down wardly and inwardly of the associated chamber. This particular action creates a sort of a curtain which serves to maintain the gas-cushion beneath the associated chamber and to prevent the gas from moving outwardly from beneath the chamber at an excess rate.

The conduit 70 extends completely around the chamber 58 as seen in FIG. 4, and, of course, is disposed at the lower portion of the chamber as heretofore described. It is evident that gas escaping through the holes in conduit 70 will create the desired air-cushion beneath the chamber 58. Similar conduits 75, 76 and 77 are provided in each of chambers 55-57 respectively, the various conduits extending peripherally around the inner surface of the lower portion of each of the chambers, the conduits being maintained in operative position by suitable straps 71 as previously described.

As seen particularly in FIG. 4, a fitting 78 is mounted adjacent one end of wall 42 and is adapted to be connected with a fitting 79 secured to one end of a flexible conduit 80, the opposite end of the conduit being adapted for connection in a conventional manner with a suitable source of gas under pressure. A valve is mounted within fitting 79 and is operated by lever 31 for controlling the flow of gas under pressure from the flexible conduit 80 into fitting 7 8 and thence to the various outlet means. By operating valve 8 1, an operator is enabled to selectively raise and lower the cargo support means. Fitting 78 is connected with a header 85 to which a. plurality of branch conduits 86, 87, 88 and 89 are connected each of these (branch conduits being connected to the header by valve means 86, 87', 83' and 89' respectively. Branch conduits 36, 87, 88 and 89 are connected respectively with the outlet conduits 76, 75, 77 and 70'. It is evident that by controlling the position of valves 86, 8'7, 88' and 89,

the amount of gas flowing from the various outlet means may be individually selectively adjustable.

Referring now to FIG. 1, the manner of employing the cargo support means thus far described is illustrated. As seen in FIG. 1, hatch cover 36 is in operative position closing its associated hatch opening and similar cargo support means 49 and 40" have already been moved into operative position with suitable break bulk cargo indicated by reference numeral 90 stacked thereon. An operator is in the proces of moving the cargo support means 4-9 with its associated load 91 to the left as seen in FIG. 1. It will be noted that the flexible conduit means 80 is attached to a conduit 95, similar conduits being provided adjacent the hatch openings over each of the cargo decks. A plurality of flexible conduits 80* may be provided and, of course, they may be provided with quick-disconnect means whereby they may be selectively connected to different ones of the supply conduits 95.

Conduits 95 are connected with a suitable central source of gas under pressure which is employed for operating all of the various cargo support means according to the present invention. It will, of course, be understood that the cargo is first stacked upon the upper supporting surface of the cargo support means.

The flexible conduit 80 is attached to the fitting 78 of the cargo support mean-s 4t} whereupon lever 81 may be actuated to open the valve in fitting 79 and thereby allow gas under pressure to enter the header 85. Valves 86, 87, 88 and 89" are open to enable the gas under pressure o-t travel to and be ejected through the holes in (the various outlet conduits 7t), 75, 76, and 77.

When gas under pressure is ejected through the holes in the outlet means of the various chambers, a gascushion will be produced, and the cargo support means will be lifted slightly off of the supporting surface. If the load is unbalanced as will commonly occur, the operator can then adjust valves 86, 87, 88 and 89 individually as necessary to either increase or decrease the flow of gas from the associated chambers so as to balance and stabilize the overall cargo support means. Once the cargo suppont means with its load is balanced upon the gas-cushion, the operator can then manually position the support means and its cargo into the desired position. When in the desired position, lever 81 may again be actuated to cut off flow of gas under pressure to the apparatus thereby removing the gas pressure and allowing the support means to come to rest upon the deck.

Referring now particularly to FIGS. 7, 9 and 10, a trailer container indicated generally by reference numeral 1% is provided, this tailcr container being of such a size and configuration as to be supported uuon the bed 101 of a trailer of a conventional tractor-trailer combination, the trailer being supported by conventional wheel assemblies 102.

As seen most clearly in FIG. 10 which illustrates a bottom view of the container, depending side walls 165 and 106 are provided along the longitudinal dimension thereof while end walls 107 and 108 are provided between opposite end portions of the side walls.

It will thus be seen that walls M5468 which depend from the bottom wall 110 of the container define a space which opens downwardly with respect to the container.

A transverse wall 111 is provided between walls 105 and 106 and longitudinally extending walls 112 and 113 are provided respectively between walls 167 and 111 and between walls 111 and 198. It will be noted that walls 111, 112, and 113 divide the space beneath the container into four symmetrical chambers in the same manner that the previously described cargo support means is divided into four chambers. Longitudinally extending bracing members 115' and transverse bracing members 116 are provided in the upper portions of each of the chambers for rigidifying and strengthening the structure.

It will be understood that each of the chambers 120, 121 122 and 123 as defined in the under surface of the container are also constructed to 'be air-tight by providing air-tight layers therein in the identical manner as heretofore described in connection with the modification shown in FIGS. 2-6. Furthermore, outlet means 125, 126, 127 and 128 are provided in chambers 12%, 121, 122 and 123 respectively, these outlet means being similar to that previously described and including a plurality of holes through which gas is ejected in a downward direction. Here again, the various outlet conduits extend around the inner periphery of the lower portions of each of the chambers and are maintained in operative position by suitable support members such as straps or the like.

Referring to FIG. 7, a fitting 134i is provided at the rear side portion of the container, this fitting being connected with a header as previously described, and four control valves 1:31, 132, 133 and 134 are provided for controlling the flow of gas under pressure to the chambers 121, 12%,

23 and 122 respectively, these valves also being employed for the purpose of balancing and stabilizing the container along with the load supported thereby.

As seen most clearly in FIGS. and 7, a pair of vertically extending channels 140 and 141 are mounted on the side wall of the container and are adapted to be engaged by suitable means on a maneuvering vehicle to facilitate handling of the container.

As seen especially in FIG. 7, a maneuvering vehicle 145 is provided, this vehicle being genera ly similar to fork lift trucks which are now in use with the exception that the clamping mechanism at the forward end thereof has been substituted for a conventional fork lift. The "ehicle is, of course, self-powered and the motor thereof drives a compressor 142 to which is connected a flexible conduit 143. As seen in FIG. 7, this flexible conduit is attached by means of a fitting 145 to the fitting 130 on the container for conducting gas under pressure to the various outlet means associated with the container.

As seen in FIG. 8, a pair of vertically extending arms 150 are provided with inturncd end portions 151 adapted to seat within the channel members 140 and 141 when swung inwardly to thereby lock the maneuvering vehicle to the container. The arms 150 are pivotally supported by upstanding posts 155 and 156 mounted on the forward end of the vehicle and the rear ends of arms 150 are pivotally attached to links 157 and 153 which are in turn pivotally attached to a rod 159 connected with the piston of a conventional hydraulic piston and cylinder arrangement.

It is evident that movement of the piston inwardly Within its associated cylinder 160 as seen in FIG. 8 will cause the arms 159 to swing inwardly thereby attaching the vehicle to the container. Conversely, when the piston is moved outwardly within the cylinder 160, arms 156 are swung outwardly to release the vehicle from the container.

When the arms are in operative engagement with the attaching means 140 and 141 on the container, move ment of the maneuvering vehicle 141 will be translated to the container so long as the container is supported on a suitable gas-cushion.

As seen in FIG. 7, the flexible conduit 143 is attached to the container and the container is supported on a gas cushion. The container has been moved partially off of the bed 101 of the trailer and is moving over the surface of a loading dock 163.

After the container has been unloaded from its truck bed, it is lifted by a crane and lowered through one of the hatch openings in the ship. As seen in FIG. 1, another maneuvering vehicle 141' identical with vehicle 141 is employed for moving the container 109 into its final position in the hold.

As seen in FIG. 1, similar containers 161' and 101" have already been moved into the desired position. It is apparent that in this manner, trailer containers may be properly positioned within the hold of a ship through,

conventional hatch openings and while employing a conventional cargo deck arrangement.

It is also apparent that whereas it is considered most expeditious to employ a maneuvering vehicle in handling large sized trailer containers, it is also possible to dispense with such maneuvering vehicles and employ a flexible conduit connected to the supply conduit within the hold for providing the gas-cushion under the trailer containers whereupon the trailer containers may be manually maneuvered into the desired position.

It is apparent from the foregoing that there is provided a new and novel method and apparatus of loading and unloading cargo in ships wherein the apparatus itself eliminates complicated and bulky structures employed in the prior art and accordingly the cost, weight and space required for this type of apparatus is substantially reduced. The apparatus is highly versatile since it can be employed for handling break bulk cargo as well as large trailer containers and the like. Means is provided for balancing and stabilizing the cargo support means thereby ensuring efficient operation thereof, such balancing being obtained merely by adjusting the valves controlling the flow of gas to the various chambers of the cargo support means. It is apparent that the method according to the present invention permits quick and easy spotting of the cargo in place while loading the ship and further it is evident that unloading of the ship may be accomplished by utilizing the very same apparatus and by reversing the steps hereinbefore described in connection with loading of the ship.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, and since the scope of the invention is defined by the appended claims, all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperative equivalents are therefore intended to be embraced by those claims.

I claitn:

1. Apparatus for loading and unloading cargo in ships comprising cargo support means having an upper portion for supporting cargo and an under portion, wall portions defining a plurality of air-tight chambers opening through said under portion, separate and independent outlet means disposed within and about the inner periphery of the lower portion of each of said chambers, said outlet means including means for directing gas under pressure inwardly of the associated chambers to provide a gas cushion beneath each of said chambers, means for connecting said outlet means with an external source of gas under pressure, and valve means for separately and individually controlling the flow of gas under pressure to the outlet means of each of said chambers to permit stabilizing and balancing of the support means.

2. Apparatus as defined in claim 1, wherein said cargo support means is substantially rectangular in plan configuration and said chambers are four in number and are symmetrically disposed with respect to the outer configuration of the cargo support means.

3. A cargo container adapted to be mounted on a truck bed, said cargo container including a peripheral wall defining a space therebeneath and opening in a downward direction, outlet means disposed within and about the inner periphery of the lower portion of said space for directing gas under pressure downwardly from said space to produce a gas-cushion beneath the container to facilitate lateral movement of the container, means for connecting said outlet means to an external source of gas under pressure, means for controlling the flow of gas from said outlet means, and attaching means on an outer surface of said container for attachment to a power operated means to facilitate lateral movement of the conta'i'er, the space beneath said container being divided into a plurality of chambers, there being separate outlet means associated with each of said chambers, and disposed about the inner periphery of the lower portion thereof, and means for individually and separately controlling the flow of gas from the outlet means in each of said chambers.

References Cited in the file of this patent UNITED STATES PATENTS 10 Hodges et a1. Apr. 21, 1953 Peterson et a1 Dec. 22, 1959 Barnett May 31, 1960 Beardsley June 19, 1962 Vaughen Sept. 25, 1962 FOREIGN PATENTS Australia Nov. 24, 1958 OTHER REFERENCES Publication: Symposium on Ground Effect Phenomena, pages 82 and 83, TL-574-G7, P7, Oct. 23, 1959. 

1. APPARATUS FOR LOADING AND UNLOADING CARGO IN SHIPS COMPRISING CARGO SUPPORT MEANS HAVING AN UPPER PORTION FOR SUPPORTING CARGO AND AN UNDER PORTION, WALL PORTIONS DEFINING A PLURALITY OF AIR-TIGHT CHAMBERS OPENING THROUGH SAID UNDER PORTION, SEPARATE AND INDEPENDENT OUTLET MEANS DISPOSED WITHIN AND ABOUT THE INNER PERIPHERY OF THE LOWER PORTION OF EACH OF SAID CHAMBERS, SAID OUTLET MEANS INCLUDING MEANS FOR DIRECTING GAS UNDER PRESSURE INWARDLY OF THE ASSOCIATED CHAMBERS TO PROVIDE A GAS CUSHION BENEATH EACH OF SAID CHAMBERS, MEANS FOR CONNECTING SAID OUTLET MEANS WITH AN EXTERNAL SOURCE OF GAS UNDER PRESSURE, AND VALVE MEANS FOR SEPARATELY AND INDIVIDUALLY CONTROLLING THE FLOW OF GAS UNDER PRESSURE TO THE OUTLET MEANS OF EACH OF SAID CHAMBERS TO PERMIT STABILIZING AND BALANCING OF THE SUPPORT MEANS. 